[PATCH 04/12] GFS2: Sort the ordered write list

Steven Whitehouse
2012-03-19T10:49:50Z

From: Bob Peterson <rpeterso@redhat.com>

This patch sorts the ordered write list for GFS2 writes.
This increases the throughput for simultaneous writes.
For example, if you have ten processes, all doing:
dd if=/dev/zero of=/mnt/gfs2/fileX
on different files, the throughput will be much better.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 4d31379..b8fe7b7 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -19,6 +19,7 @@
#include <linux/freezer.h>
#include <linux/bio.h>
#include <linux/writeback.h>
+#include <linux/list_sort.h>

#include "gfs2.h"
#include "incore.h"
@@ -566,6 +567,20 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
log_write_header(sdp, 0, 0);
}

+int bd_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+ struct gfs2_bufdata *bda, *bdb;
+
+ bda = list_entry(a, struct gfs2_bufdata, bd_le.le_list);
+ bdb = list_entry(b, struct gfs2_bufdata, bd_le.le_list);
+
+ if (bda->bd_bh->b_blocknr < bdb->bd_bh->b_blocknr)
+ return -1;
+ if (bda->bd_bh->b_blocknr > bdb->bd_bh->b_blocknr)
+ return 1;
+ return 0;
+}
+
static void gfs2_ordered_write(struct gfs2_sbd *sdp)
{
struct gfs2_bufdata *bd;
@@ -573,6 +588,7 @@ static void gfs2_ordered_write(struct gfs2_sbd *sdp)
LIST_HEAD(written);

gfs2_log_lock(sdp);
+ list_sort(NULL, &sdp->sd_log_le_ordered, &bd_cmp);
while (!list_empty(&sdp->sd_log_le_ordered)) {
bd = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_bufdata, bd_le.le_list);
list_move(&bd->bd_le.le_list, &written);
--
1.7.4